This invention relates to hand tools, and more particularly to a device, commonly known as a level, for indicating the angular relationship of a substantially flat work surface to level, plumb, or other datum.
A spirit level generally consists of a frame providing flat horizontal top and bottom surfaces adapted for placement on a work surface. One or more spirit vials are mounted to the frame in a predetermined orientation relative to the top and bottom surfaces of the level. In a typical application, three vials are mounted to the frame. The central vial is oriented such that its longitudinal axis is parallel to the planes of the top and bottom surfaces. One of the end vials is oriented such that its longitudinal axis is oriented perpendicular to the planes of the top and bottom surfaces. The other end vial may have an orientation similar to that of the first-mentioned end vial, or it may be positioned such that its longitudinal axis is oriented 45.degree. to the plane of the top and bottom surfaces.
It is known to provide an opening in the top surface of the level to extend the range of positions from which the level-indicating vial can be viewed. This topreading feature is shown in Johnson U.S. Pat. No. 4,011,660 issued Mar. 15, 1977; Mayes U.S. Pat. No. 4,492,038 issued Jan. 8, 1985, and Rawlings et al U.S. Pat. No. 4,765,061 issued Aug. 23, 1988.
It is an object of the present invention to provide an improvement to a top-reading feature associated with a level, such as is exemplified in the noted patents. Specifically, the present invention has as its object to provide magnification of the level vial when viewed through the opening formed in the top surface of the level, to enhance the advantages provided by the top-reading feature. It is a further object of the invention to provide a top-reading level, with magnification of the vial, in which the magnifying element is secured within the opening in an advantageous manner.
The invention is employed in combination with a level of conventional construction, which typically comprises horizontal top and bottom surfaces, with an interposed body portion in which a cavity is formed. A vial is located within the cavity for providing an indication of the relationship to level, or other datum, of the work surface when the bottom surface is placed thereon. In accordance with one aspect of the invention, an opening is formed in the top surface of the level, and is in visual communication with the cavity to allow the vial to be viewed through the opening. A transparent magnifying element is located between the vial and the opening for providing magnification of the vial when viewed through the opening. In one form of the invention, the level consists of a frame having upper and lower horizontal flanges with a vertical web disposed therebetween, with the cavity in the level body portion comprising a vial-receiving opening formed in the web. A pair of vial covers are located one on either side of the web, defining an internal cavity within which the vial is located. Each vial cover defines a window opening for providing visual access to the vial therethrough. A transparent lens is located within each window opening, and is positioned between one of the vial covers and a side of the web. The magnifying element is formed integrally with a first one of the lenses. The first lens includes a laterally extending upper portion, and the magnifying element is defined by the first lens upper portion. Each of the lenses includes structure which engages the underside of the upper flange adjacent the opening, for sealing the internal cavity defined by the vial covers within which the vial is located. Each of the lenses is provided with an upper portion extending above the upper surface of its associated vial cover, and the lens upper portions are provided with mating structure for interlocking the lenses together. The mating structure preferably comprises a tongue-and-groove arrangement. In addition, a connection arrangement is provided for securing each lens to its associated vial cover. The connection arrangement consists of one or more locking tabs located adjacent the window opening formed in each vial cover, and engagement structure, in the form of protrusions, provided on each lens for engagement with the locking tabs to secure the lenses to the vial covers.
The invention further contemplates an improvement in a level, and a method of making a level, substantially in accordance with the foregoing summary.
Various other objects, features and advantages of the invention will be made apparent from the following description taking together with the drawings.